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A Dry Contact Is a Potential Free Contact a Dry Contact Is a Contact That Does

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A Dry Contact Is a Potential Free Contact a Dry Contact Is a Contact That Does A dry contact is a potential free contact A dry contact is a contact that does not provide voltage. For instance, the push-to-talk switch of a microphone, which just closes a circuit without providing voltage. A wet contact is a contact that will provide voltage when closed, like the switch on the wall that activates the 110 VAC outlet to turn a lamp on in a room. Potential free contact, voltage free contact and dry contact, they all are same. The dry contact is the contact which is physically operated with the main device, but not electrically connected to it. It is a voltage free on/off contact and can be used in any system. The auxiliary contact of the motor contactor used for the motor run feed back is the example of the dry contact. The contacts of the interposing relays are also dry contacts. - MS Perhaps you mean "dry circuit"? Contacts which need to work in such circuits are generally gold-plated, since the current and voltage levels are too low to break down the contaminant layWhat is a volt free contact? Answer: A volt free contact is a set of contacts that uses a voltage source from another location. The contacts are used to tie two individual pieces of electrical equipment together so the action on one will cause the other piece of equipment to operate. It is just a new way of using the older terminology "dry contacts". An example of use is the diesel start contacts on an automatic transfer switch. When the transfer switch is in the utility (hydro) position the diesel start "dry contacts" located in the transfer switch are open. On a power failure the transfer switch disconnects from the utility and connects to the generator position. When the transfer switch moves to the generator connect side the "dry contacts" , or volt free contacts, in the transfer switch close. This allows a voltage from the generator control panel (usually 24 volts DC) to return to the start relay located in the generator control panel. This relay engages the starter and starts the diesel generator. On return of utility power the reverse action takes place and the volt free contacts return to their normal state of normally open.er on conventional contacts... Generally that means the open circuit voltage is 20mV or less and the short circuit current is 100mA or less. Potential /Volt free" or "dry contacts" are used when the equipment being controlled has its own power supply e.g.,PLC's have a 24 VDC power source in them . The external contact used to start the motor/equipment is a dry contact, and it switches the voltage supplied by the PLC's .The output modules in PLC uses Interposing relay connected to MCC , the dry contact connects the drive input to the PLC's 24 VDC and powers the drive circuit input. The internal devices sense the voltage, start the drive, and the current and voltage is returned to the PLC's own power supply through internal circuitry. A volt free contact is a contact without any voltage on it. It is usually supplied in a system for other parties to use and they then supply their own voltage into their own system eg: to a BMS system. A dry contact is just that - dry - as opposed to a wet contact that is usually something like a mercury switch or it can also have a mercury wetted contact. A proximity contact is one I have never heard of but would assume it is meant to be a proximity switch of somw type, probably with a transistor output of the open collector variety. Volt-free and dry contact mean the same thing. If a control system supplier offers a dry contact for you to read as a status bit, then he is offering to close a contact (relay or contact output) that is nothing more that a stand-alone set of contacts with no voltage, current, or anything else impressed across the contact set. It becomes the user's responsibility to determine how to sense that contact closure. Usually you do this by putting a voltage on one side and sensing the voltage on a return line from the other side of the contact when it closes. Once you apply voltage to the contacts, it becomes a wet contact. You "wet" the contact with a sensible voltage level. A proximity contact is a contact set that makes without any kind of direct coil or physical actuation of the contact set. Proximity contacts or switches are usually either optical devices that switch because a light beam is broken or completed, or in some cases magnetic switches are called proximity contacts. The contact set will open or close when a magnet gets close enough to cause the switch action like a door switch on a burglar alarm. .
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